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Re: modulo regridding



Hi Ansley,
Now I understand why the demo described in User Guide is OK.
Unfortunately, I don't understand why it's not the case for my data.
Here below is the copy of the ferret output
Including a time range for the variable beeing regridded with month_reg@lin
does not change results: this variable is not defined in a correct way.
If you have some idea ...
Thanks.
Francois Delclaux



umhyd_delclaux% ferret
        NOAA/PMEL TMAP
        FERRET v5.40 
        Linux 2.4.3-12smp - 02/19/02
        13-Jun-05 14:11    

yes? use atm_era40.nc
yes? sh d/v
     currently SET data sets:
    1> ./atm_era40.nc  (default)
 
 name     title                             I         J         K         L
 PV       Potential vorticity              1:144     1:73      1:2       1:540
             K m**2 kg**-1 s**-1 on grid GNL1 with -0.0001321826 & -32767 for mi
ssing data
             X=1.2W(-1.2):1.2W  Y=91.2S:91.2N  Z=-125:1375 
 GEO      Geopotential                     1:144     1:73      1:2       1:540
             m**2 s**-2 on grid GNL1 with -3089.586 & -32767 for missing data
             X=1.2W(-1.2):1.2W  Y=91.2S:91.2N  Z=-125:1375 
 TEMP     Temperature                      1:144     1:73      1:2       1:540
             K on grid GNL1 with 196.2303 & -32767 for missing data
             X=1.2W(-1.2):1.2W  Y=91.2S:91.2N  Z=-125:1375 
 U        U velocity                       1:144     1:73      1:2       1:540
             m s**-1 on grid GNL1 with -23.0944 & -32767 for missing data
             X=1.2W(-1.2):1.2W  Y=91.2S:91.2N  Z=-125:1375 
 V        V velocity                       1:144     1:73      1:2       1:540
             m s**-1 on grid GNL1 with -31.70974 & -32767 for missing data
             X=1.2W(-1.2):1.2W  Y=91.2S:91.2N  Z=-125:1375 
 Q        Specific humidity                1:144     1:73      1:2       1:540
             kg kg**-1 on grid GNL1 with 6.80608E-07 & -32767 for missing data
             X=1.2W(-1.2):1.2W  Y=91.2S:91.2N  Z=-125:1375 
 W        Vertical velocity                1:144     1:73      1:2       1:540
             Pa s**-1 on grid GNL1 with -0.7332675 & -32767 for missing data
             X=1.2W(-1.2):1.2W  Y=91.2S:91.2N  Z=-125:1375 
 VO       Vorticity (relative)             1:144     1:73      1:2       1:540
             s**-1 on grid GNL1 with -0.00008048117 & -32767 for missing data
             X=1.2W(-1.2):1.2W  Y=91.2S:91.2N  Z=-125:1375 
 D        Divergence                       1:144     1:73      1:2       1:540
             s**-1 on grid GNL1 with -0.00004415594 & -32767 for missing data
             X=1.2W(-1.2):1.2W  Y=91.2S:91.2N  Z=-125:1375 
 R        Relative humidity                1:144     1:73      1:2       1:540
             % on grid GNL1 with -4.914274 & -32767 for missing data
             X=1.2W(-1.2):1.2W  Y=91.2S:91.2N  Z=-125:1375 
 O3       Ozone mass mixing ratio          1:144     1:73      1:2       1:540
             kg kg**-1 on grid GNL1 with 9.47E-10 & -32767 for missing data
             X=1.2W(-1.2):1.2W  Y=91.2S:91.2N  Z=-125:1375 
 
  time range: 01-SEP-1957 12:00 to 01-AUG-2002 12:00
 
yes?  use climatological_axes
 *** NOTE: regarding /home/delclaux/ferret/climatological_axes.cdf ...
 *** NOTE: Climatological axes SEASONAL_REG, MONTH_REG, and MONTH_IRREG defined

! defining a new variable div at one point (x,y,z)
yes? let div=10e06*d[d=1,k=1,i=10,j=10]

! listing div variable for a 3 year period
yes? list/t="01-jan-1960":"1-dec-1962" div
             VARIABLE : 10E06*D[D=atm_era40.nc,K=1,I=10,J=10]
             SUBSET   : 36 points (TIME)
             LONGITUDE: 22.5E
             LATITUDE : 67.5S
             HEIGHT (millibars): 250
                        22.5E
                        10
 01-JAN-1960 12 / 29:  -0.15
 01-FEB-1960 12 / 30:  11.22
 01-MAR-1960 12 / 31:   0.16
 01-APR-1960 12 / 32:   4.11
 01-MAY-1960 12 / 33:   0.63
 01-JUN-1960 12 / 34: -10.50
 01-JUL-1960 12 / 35:  11.68
 01-AUG-1960 12 / 36:   5.09
 01-SEP-1960 12 / 37:  -2.97
 01-OCT-1960 12 / 38: -11.34
 01-NOV-1960 12 / 39:  -4.70
 01-DEC-1960 12 / 40:  -0.14
 01-JAN-1961 12 / 41:  -1.19
 01-FEB-1961 12 / 42:  -6.27
 01-MAR-1961 12 / 43:  17.33
 01-APR-1961 12 / 44:  -2.21
 01-MAY-1961 12 / 45:  -6.09
 01-JUN-1961 12 / 46:  -1.26
 01-JUL-1961 12 / 47:  23.96
 01-AUG-1961 12 / 48: -17.12
 01-SEP-1961 12 / 49:  -2.58
 01-OCT-1961 12 / 50:  12.22
 01-NOV-1961 12 / 51:  -5.44
 01-DEC-1961 12 / 52:   2.17
 01-JAN-1962 12 / 53:  -3.58
 01-FEB-1962 12 / 54:  -8.62
 01-MAR-1962 12 / 55:  -3.75
 01-APR-1962 12 / 56:  -2.16
 01-MAY-1962 12 / 57: -13.72
 01-JUN-1962 12 / 58: -15.80
 01-JUL-1962 12 / 59:  -3.27
 01-AUG-1962 12 / 60: -14.88
 01-SEP-1962 12 / 61:  -0.61
 01-OCT-1962 12 / 62:  -3.05
 01-NOV-1962 12 / 63:  -1.09
 01-DEC-1962 12 / 64:  -8.30

! defining a regridded variable divc by interpolation on month_reg axis
yes?  let divc=div[gt=month_reg, t="01-SEP-1957":"01-AUG-2002"]

! listing divc variable
yes? list/t="01-jan-1960":"1-dec-1962" divc
             VARIABLE : DIV[GT=MONTH_REG, T="01-SEP-1957":"01-AUG-2002"]
             SUBSET   : 36 points (TIME)
             LONGITUDE: 22.5E
             LATITUDE : 67.5S
             HEIGHT (millibars): 250
                       23E
                       10
 17-DEC-1959 / 23520:....
 16-JAN-1960 / 23521:....
 15-FEB-1960 / 23522:....
 17-MAR-1960 / 23523:....
 16-APR-1960 / 23524:....
 17-MAY-1960 / 23525:....
 16-JUN-1960 / 23526:....
 17-JUL-1960 / 23527:....
 16-AUG-1960 / 23528:....
 16-SEP-1960 / 23529:....
 16-OCT-1960 / 23530:....
 15-NOV-1960 / 23531:....
 16-DEC-1960 / 23532:....
 15-JAN-1961 / 23533:....
 15-FEB-1961 / 23534:....
 17-MAR-1961 / 23535:....
 17-APR-1961 / 23536:....
 17-MAY-1961 / 23537:....
 16-JUN-1961 / 23538:....
 17-JUL-1961 / 23539:....
 16-AUG-1961 / 23540:....
 16-SEP-1961 / 23541:....
 16-OCT-1961 / 23542:....
 16-NOV-1961 / 23543:....
 16-DEC-1961 / 23544:....
 16-JAN-1962 / 23545:....
 15-FEB-1962 / 23546:....
 17-MAR-1962 / 23547:....
 17-APR-1962 / 23548:....
 17-MAY-1962 / 23549:....
 17-JUN-1962 / 23550:....
 17-JUL-1962 / 23551:....
 17-AUG-1962 / 23552:....
 16-SEP-1962 / 23553:....
 16-OCT-1962 / 23554:....
 16-NOV-1962 / 23555:....



Ansley Manke a écrit:
Hi Francois,
When you define the variables for centering, give the variable definitions a time range. When using linear regridding instead of modulo regridding, Ferret tries to regrid to the time range of the modulo axis, which is 16-jan-0000 to 16-dec-0000  (do "show axis month_reg" to see this). Since your time data in the range 1957 to 2002 doesn't overlap with the year 0000, there is no result. To regrid a time series variable to a modulo axis and have it apply to the time range of the variable,

   let divc = div[gt=month_reg,t="01-SEP-1957 12:00":"01-AUG-2002 12:00"]

Modulo time axes are defined to have a time in year 0000 or 0001 for convenience, but this is a case where this choice causes some confusion.  I believe this will solve your problem.

Ansley





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